Flash lamp



E. LEMMERS FLASH LAMP Filed March 13, 1937 Inventor. Eugene Lemmers, y g a 1 W Hi Attorney Patented @ct. 3i, i93$ stares FLASH LAW New York Application March 13,

6 Claims.

My invention relates to flash lamps and more particularly to that type of flash lamp used for photographic purposes which usually comprises a sealed transparent bulb in which is enclosed a readily combustible material,-such as metal foil or wire, together with a substance, usually a gas filling, which upon ignition enters into a reaction with the combustible material with the resulting emission of actinic light.

10 To initiate the actinic reaction it is necessary to provide some form of ignition means therefor. The type of ignition means customarily employed for such purpose comprises a resistance element or filament embedded in a head of ignition paste l5 and supported within the bulb in close proximity to the combustible material by a conventional mount structure. The ignition paste generally used is extremely sensitive, and when the electrical circuit through the filament is energized,

the heated filament promptly ignites the head of ignition paste which in turn ignites the combustible material, thus initiating the actinic reaction.

. As a safeguard against explosion of the glass bulb when a lamp of this type is flashed, it is customary to test the same for the presence of air. One desirable method of conducting such a test, known as a coil test, consists in the use of high frequency equipment employing glow tubes.

Ithas been found, however, that such a method of testing results in the loss of a great number of flash lamps through the premature flashing of the same, termed flashouts, which premature flashing is caused by the ignition of the extremely sensitive head of ignition paste by the high frequency of the test equipment. Furthermore, the bead of ignition paste is very fragile and frequently cracks or breaks off during shipment of the lamp. I have accordingly devised a novel form of ignition means or primer head for flash lamps which will prevent the premature flashing of the same, and which possesses increased mechanical strength and resistance to cracking and breaking off.

One object of my invention is to provide an improved flash lamp which will not flash prematurely when subjected to various external phenomena, such as high frequency, corona, or the like.

Another object of my invention is the provision of a novel formof ignition means for flash lamps which will not ignite when subjected to various external phenomena, such as sparks induced by high frequency corona, and the like.

as A further object of my invention is the prolacquer.

1937, Serial No. 130,723

vision of a coating of'lacquer or other similar non-conducting material on the primer bead of a flash lamp, which coating excludes such paste from various external phenomena normally tending to ignite the same. I

A still further object of my invention is the provision of a coating of non-conducting material on the primer bead of a flash lamp, which coating may consist of nitrocellulose, cellulose acetate or other lacquer, or a varnish, paint, glue 10 or similar compound.

Another object of my invention is the provision of a coating on the primer head of a flash lamp which coating adds mechanical strength to such bead and prevents the same from cracking l5 and breaking oil.

Other objects and advantages of my invention will be apparent from the following description of an embodiment thereof, taken in conjunction with the accompanying drawing, in which:

Fig. l is an elevation of a flash lamp comprising my invention in which the ignition means comprises a bead of ignition paste enclosing the fllament and coated with a layer of non-conductive material, and 25 Fig. 2 is an enlarged fragmentary sectional view of a portion of a head of ignition paste coated in accordance with my invention.

Referring to Fig. 1, the lamp comprises a vitreous transparent bulb i0 containing a small 30 filament H, the ends of which are connected to lead-in wires i2, I2 which extendv through a stem 83 to the base It. The filament ii is em-' bedded in a fulminating substance E5 to thereby form the ignition means for the lamp. A disc it, 35 preferably of asbestos, is mounted on the stem it to shield the base end of the lamp from the heat of combustion. The bulb I0 is loosely fllled with combustible material ii, consisting of metal foil or wire, usually of aluminum. 40

The fulminating substance or primer head it customarily employed in flash lamps of the type described above is composed of an extremely sen-- sitive metal powder it, such as zirconium metal, mixed with a suitable binding material, such as 45 When a head of this paste dries, the metal powder particles at the surface protrude therefrom} and under the microscope have the appearance of fuzz. It is this fuzz that causes the head of metal powder to flash when a slight 50 spark or even corona strikes the same. By covering this fuzz or roughened surface with a coating of a suitable non-conductive substance l9, as shown in Fig. 2, the metal powder i8 is thereby excluded from the action of all external phe- 5s suitable non-conductive substance, such as nitrocellulose, cellulose acetate, or other lacquer, or may even consist of a varnish, paint, glue or similar compound. This coating may be applied to the bead or fulminating substance or metal powder II by simply dipping such head in the coating material and allowing the latter to dry 3 thereon. i

Although the above described method of preventing premature flashing of the fulminating substance II and adding mechanical strength thereto is-the preferred method, the same eflect as may be' obtained to a certain degree by mixing the metal powder with-a great excess of binder, the latter thus tending to produce a bead having a smooth outer surface instead ofv the customary roughened surface. a What I claim as new and desireto secure by Letters Patent of theU'nited States is:

. l. A flash lamp comprising a sealed container, a quantity of combustible material within said container, and means for igniting said combustible material, said means including a body of highly sensitive fulminating substance comprising a readily ignitable metallic powder and coated with a layer of non-conductive material capable of preventing premature ignition of the fulminat o ing substance during a high frequency test for the-presence of air in said container.

2. A flash lampcomprising a sealed container,

a quantity of combustible material within said container, and means for igniting said combustible material, said means including a body of highly sensitive fulminating substance comprising a readily ignitable metallic powder and coated with a layer of lacquer.

3. A flash lamp comprising a sealed container, I

ing a readily ignitabie metallic powder and coated with a layer of cellulose acetate.

5. A flash lamp comprising a sealed container, a quantity of combustible material within said container, and means for igniting said combustible material, said means including a body of highly sensitive fulminating substance comprising a readily ignitable metallic powder and coat-.- ed with a layer of varnish.

6. A flash lamp comprising a sealed container, a quantity of combustible material within said container, and means for igniting said combustible material, said means comprising an electrical translation element embedded in a bead of high- 1y sensitive fulminating substance comprising a readily ignitable metallic powder, said bead being coated with a layer of non-conductive material which strengthens said head against breakage and is capable of preventing premature ignition of the fulminating substance during a high frequency test for the presence of air in said container.

EUGENE 

